js实现加密解密_js实现解密-优快云博客

本文提供了一种基于用户自定义密码的文本加解密算法的JavaScript实现。该算法通过复杂的数学运算生成加密密钥，并利用该密钥对输入字符串进行逐字符加密，最终返回经过16进制编码的加密字符串。同时，也提供了相应的解密函数以还原加密前的原始信息。

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废话不多说,直接上代码:

 <!-- Begin 
    function encrypt(str, pwd) {
        if (pwd == null || pwd.length <= 0) {
            alert("Please enter a password with which to encrypt the message.");
            return null;
        }
        var prand = "";
        for (var i = 0; i < pwd.length; i++) {
            prand += pwd.charCodeAt(i).toString();
        }
        var sPos = Math.floor(prand.length / 5);
        var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos * 2) + prand.charAt(sPos * 3) + prand.charAt(sPos * 4) + prand.charAt(sPos * 5));
        var incr = Math.ceil(pwd.length / 2);
        var modu = Math.pow(2, 31) - 1;
        if (mult < 2) {
            alert("Algorithm cannot find a suitable hash. Please choose a different password. \nPossible considerations are to choose a more complex or longer password.");
            return null;
        }
        var salt = Math.round(Math.random() * 1000000000) % 100000000;
        prand += salt;
        while (prand.length > 10) {
            prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();
        }
        prand = (mult * prand + incr) % modu;
        var enc_chr = "";
        var enc_str = "";
        for (var i = 0; i < str.length; i++) {
            enc_chr = parseInt(str.charCodeAt(i) ^ Math.floor((prand / modu) * 255));
            if (enc_chr < 16) {
                enc_str += "0" + enc_chr.toString(16);
            } else enc_str += enc_chr.toString(16);
            prand = (mult * prand + incr) % modu;
        }
        salt = salt.toString(16);
        while (salt.length < 8) salt = "0" + salt;
        enc_str += salt;
        return enc_str;
    }

    function decrypt(str, pwd) {
        if (str == null || str.length < 8) {
            alert("A salt value could not be extracted from the encrypted message because it's length is too short. The message cannot be decrypted.");
            return;
        }
        if (pwd == null || pwd.length <= 0) {
            alert("Please enter a password with which to decrypt the message.");
            return;
        }
        var prand = "";
        for (var i = 0; i < pwd.length; i++) {
            prand += pwd.charCodeAt(i).toString();
        }
        var sPos = Math.floor(prand.length / 5);
        var mult = parseInt(prand.charAt(sPos) + prand.charAt(sPos * 2) + prand.charAt(sPos * 3) + prand.charAt(sPos * 4) + prand.charAt(sPos * 5));
        var incr = Math.round(pwd.length / 2);
        var modu = Math.pow(2, 31) - 1;
        var salt = parseInt(str.substring(str.length - 8, str.length), 16);
        str = str.substring(0, str.length - 8);
        prand += salt;
        while (prand.length > 10) {
            prand = (parseInt(prand.substring(0, 10)) + parseInt(prand.substring(10, prand.length))).toString();
        }
        prand = (mult * prand + incr) % modu;
        var enc_chr = "";
        var enc_str = "";
        for (var i = 0; i < str.length; i += 2) {
            enc_chr = parseInt(parseInt(str.substring(i, i + 2), 16) ^ Math.floor((prand / modu) * 255));
            enc_str += String.fromCharCode(enc_chr);
            prand = (mult * prand + incr) % modu;
        }
        return enc_str;
    }
    // End -->